964 C4AWD/ABS warning lights...need some guidance
 

Hello all, I picked up a 1990 964 C4 a month or so ago. The car needed some TLC but overall its a pretty good little 964 to knock around in.

The folks I bought it from mentioned the AWD light was on but they were able to get it to go off by replacing one of the accelormeters. When I received the car it was back on. I also notice a bunch of the warning lights were not coming on. So after playing around with the bulbs it was lighting up like a Christmas tree. I was able to resolve everything pretty easy but I just cant seem to get the AWD/ABS lights to go off.

I have gone through the below list of trouble shooting so I'm hoping someone may have another idea of what to try next.

Some info about the driving characteristics:

Before I did anything to the car the warning lights would come on almost instantaneously once I got over about 3 mph. Now,after doing the below, I can almost get out of my neighborhood about a 100yards but staying under 20mph. When I stop at the stop sign I can always feel the brake pedal give a bit...still no warning lights. after accelerating once I get up to about 20-25mph the AWD warning light goes off followed by the ABS about 5 seconds later. The brakes only settle as mentioned above that one time. Hopefully that all gives some clues as to what the issue might be:

Things I've tried:

ABS/PDAS

*Soldered Clock Cold Solder Joints - did this which resolved airbag/seatbelt lights
*Front boot crash sensor connectors-Cleaned contacts
*Replaced both accelerometers with newer solid state version
*Cleaned all 4 wheel sensors
*Relays-Replaced ABS, Brake booster, and fuel pump relays whith new
* Alternator - tested alternator and it was fine
*Check battery voltage -battery tested over 12 volts
* Checked PDAS control unit connection and cleaned connections
* Check pressure switch seal-no leaks detected
*checked and cleaned Ground wire behind pressure switch plug-
*Adjusted brake fluid reservoir level
*Checked ABS power connection at battery and cleaned


Any advice is greatly appreciated!! Thanks

Pic for fun...

http://forums.pelicanparts.com/uploa...1490299465.jpg

They're notoriously sensitive to bad coils and/or plug wires. How much time on those? Be aware that the currently available coils are also know to fail early; while I've had good luck with mine when next they're due I'll swap in the 993 coil packs. There's good info at the Rennlist forum; the 964 community there is a bit more active than the one here.

Are you adjusting your brake fluid with the car running? It needs to be at max with the engine on.

+1 on the 993 coil packs. Easy to do, if you look at the build thread in my signature here, follow the link, I explain making this switch.

Can you pull the codes using the Scantool or Durametric or Hammer?

Porterdog and Spyerx, thanks for responding. Yes, I've read several threads on rennlist about the coils and wires. Hadn't heard about the crappy quality of the new 964 coils now available. I will look into the 993 conversion. Also, yes, I've adjusted the brake fluid with the car on.

I really dont know the age of the existing coils and the wires but I suspect they've probably been on the car for most of its life. I'll try the coils next and see if thats it before tackling the wires. The plug wires seems like a major hassle.

I do have access to a Durametric scan tool from a friend but he's about a two hour round trip so not easily accessible.